1. Field of the Invention
The invention relates to a method of manufacturing a semiconductor element. Specifically the invention relates to a technique to form a nitride-semiconductor thin film that is used for forming a light emitting element.
2. Description of Related Art
Nitride semiconductors, such as GaN (gallium nitride) semiconductors, are used in light emitting elements, such as laser diodes and light-emitting diodes. A nitride semiconductor of this kind has a high melting point, which makes the manufacturing of large-diameter wafers difficult. For this reason, a conventional manufacturing method starts with an epitaxial growth process of a nitride semiconductor layer on top of a substrate of a different kind of material—specifically, a sapphire substrate. Then, laser beams are irradiated onto the interface between the sapphire substrate and the nitride semiconductor layer, and thus the thin-film semiconductor layer is separated from the sapphire substrate (this method is known as the laser lift-off method).
However, the sapphire substrate serving as the base-material substrate for the epitaxial growth is expensive. In addition, there are many lattice defects in the epitaxial layer of the nitride semiconductor thus separated by the laser lift-off method, which makes the obtaining of light emitting elements of high light-emitting efficiency impossible.